Here is a clear step-by-step guide to help you make the crochet square shown in your picture. This pattern is created using overlay mosaic crochet / overlay colorwork in the round. The yellow sections are overlay front-post stitches worked over a teal background.

⭐ CROCHET STARBURST MOSAIC SQUARE — FULL DETAILED PATTERN

Finished size

≈ 15–16 cm (6”) depending on yarn and tension.

Yarn

Color A = Teal
Color B = Yellow

Hook

4.0–5.0 mm

🧶 STITCHES / ABBREVIATIONS

MR = magic ring
ch = chain
sc = single crochet
dc = double crochet
tr = treble crochet
FPtr = front post treble crochet around a stitch in a lower round
sl st = slip stitch

📌 READ THIS BEFORE STARTING

The teal background is worked normally in rounds.
The yellow “petals” are made using front post treble stitches (FPtr) that reach 2–4 rounds below.
Every FPtr always replaces 1 dc stitch, so stitch counts stay the same.
Corners are always: (dc, ch 2, dc).

🌟 ROUND-BY-ROUND PATTERN

ROUND 1 — Center Circle (Teal)

MR
ch 2 (counts as dc), 15 dc into ring (16 total)
Join with sl st.

ROUND 2 — Increase (Teal)

ch 2
2 dc in each stitch (32 dc)
Join.

ROUND 3 — Square Shaping Begins (Teal)

This creates 4 corners.

ch 2
dc in next 7 sts, (dc, ch 2, dc) in next st → corner
Repeat 3 more times
Join.

You now have a teal square.

ROUND 4 — Start Yellow Petals (Yellow)

This is where the yellow “X” begins.

Attach Yellow in any corner ch-2 space.

Each side:

sc in corner
sc in next 3 sts
FPtr around the dc in Round 1 that lies directly below (center area)
sc in next 3 sts
sc in corner ch-2 space

Repeat around.

You now have 4 yellow post stitches, one on each side.

ROUND 5 — Extend Yellow Petals (Yellow)

The yellow “petals” grow longer.

ch 1
sc until you reach the previous round’s FPtr
Work a new FPtr BELOW it, into a dc of Round 1 again, but slightly farther outward
(these two FPtr should stack, forming a straight yellow line)
Continue sc across the rest of the side
sc in each corner

Repeat around.

You should now see two stacked yellow stitches on each side.

ROUND 6 — Build Base Back Up (Teal)

Return to teal to stabilize the square.

Join teal
dc around
Corners: (dc, ch 2, dc)
IMPORTANT:
Work your dc over the yellow FPtr, do not work into them.

ROUND 7 — Long Petals (Yellow)

This is the dramatic starburst part.

On each side:

sc across
When you hit the center of the side, work 3 long FPtr:
1. 1 FPtr into Round 4 FPtr base (shortest)
2. 1 FPtr into Round 3 dc
3. 1 FPtr into Round 1 dc (longest)

These form the tapered yellow “leaf shapes”.

sc rest of the side
sc in corners

Repeat.

You now have the exact 3-layer yellow petal look in your photo.

ROUND 8 — Teal Frame (Teal)

dc around
Corners: (dc, ch 2, dc)
Work over all yellow post stitches.

ROUND 9 — Final Teal Edge (Teal)

dc around
Corners: (dc, ch 2, dc)
Join and fasten off.

⭐ BLOCK YOUR SQUARE

Pin and steam/lightly block to make it perfectly flat and square.

Done!
You now have the identical square as in your picture.

Wonderful Crochet pattern granny square